Twenty-five families, 22 of them now Jewish, have been identified via DNA testing as descendants of a common paternal ancestor who lived several hundred years ago. The families were connected through Family Tree DNA, a DNA testing company with a large Jewish database. Using DNA in genealogical research is becoming increasingly common, and many people test themselves because they’re curious about their origins. Individuals who match are put into contact with one another.

In this case, a host of genealogical questions remain: What was the time period, location and identity of the common ancestor, and what were the migration routes of his descendants?

One possibility labels the common ancestor as Sephardi. With the modern families mostly of recent Eastern European descent, that would challenge their identities on the most basic level.

Vienna-born electrical engineer Herbert Huebscher, 80, of Franklin Square, N.Y., spearheaded the project, together with South African-born Dr. Saul Issroff, who now lives in London.

It began when Huebscher was tested, and Issroff was the only exact match in the database of Family Tree DNA, one of the leading companies doing this kind of testing. Extended testing showed just a small genetic difference, making them “genetic cousins.” They, like the families, matched on 37 genetic “markers.”

The Jewish families’ origins are in Galicia, Podolia, Crimea, Belarus, Lithuania and Latvia — the Pale of Settlement; five are Levites. In Puerto Rico, one recently learned of possible Jewish ancestry; those from Germany and Hungary suspected it, but do not consider themselves Jewish. Today, the families live mostly in the United States and United Kingdom.

The families share rare Y-DNA anomalies as well as the 37 “markers,” making a common ancestor a virtual certainty, company founder Bennett Greenspan says.

Huebscher “has applied the genetic genealogy breakthrough in exactly the way I dreamed. He broadened his approach, cast a wide net and found a tight group of genetic cousins,” Greenspan says.

Y-DNA, carried only by males, doesn’t change except for minor mutations. This Y-DNA is transmitted by father to son, for thousands of years.

The test takes only a few seconds. A toothbrush-like scraper is rubbed into the inner cheek, then placed in a special tube and mailed to Family Tree DNA.

Huebscher and Issroff will present the genealogical puzzle at the 26th IAJGS International Conference on Jewish Genealogy, to be held Aug. 13-18, in New York City. More information is available at www.jgsny2006.org.

Huebscher enjoys “the challenge of delving into the genealogical puzzle” and investigating their common ancestor’s identity, time period and location, as well as the migration routes that produced different names and locations.

Why just five of the families should be Levites, descendants of a patrilineal clan that assisted the Israelite priests during ancient times, is another puzzle. Huebscher’s theories: A Levite shortage might have influenced leaders to appoint new Levites, or some Jews might have falsely claimed to be Levites.

Levite status may have been forgotten as religious observance waned or as victims of pogroms or epidemics left small children unaware of their status. Huebscher, for example, had no idea his family members were Levites until a second cousin, 88, had a childhood memory of his father saying, “We have to leave the shul while the Cohanim are duchening [delivering the priestly blessing] because we are Levites.”

One expert voiced skepticism.

“If individuals match genetically, they are related,” says Dr. Doron Behar, a population geneticist at Rambam Medical Center in Haifa. “However, that genetic match is just that. It does not confirm the religion or ethnic background of those individuals.”

Behar urges some caution. “Genetic genealogy is a very important tool — one that is having a great impact on the field of genealogy in general,” he says. “But it is only one of the tools that researchers use today in their search for genealogical truth, and results need to be interpreted with caution.”

A key connection between the Eastern European Jews and their Sephardi ancestry is researcher and avid genealogist Sonia Rosa-Velez of Virginia. Her earliest traced roots are in Aguada, Puerto Rico, in 1860, with her great-grandfather Saturnino Rosa.

Prior to the testing of her father, Pascual Rosa-Feliciano in Aguada, the family had no knowledge of Jewish roots.

Historians agree that Columbus’ crews included known conversos, Jews who converted to avoid persecution during the Spanish Inquisition. On his second voyage, Columbus arrived in Puerto Rico with 1,500 men in 17 vessels.

A Catholic church was built in Aquada. Huebscher says there were almost no self-declared Jews in Puerto Rico before about 1890. By definition, he says, Saturnino’s ancestor must have been a converso.

“How else could he have had the Y-DNA of our group and lived in Puerto Rico?”